Thermal Transport in Crystalline and Non-crystalline Solids: Theory and Experiments: Interfaces
Sponsored by: TMS Structural Materials Division, TMS: Nuclear Materials Committee
Program Organizers: Marat Khafizov, Ohio State University; Michael Manley, Oak Ridge National Laboratory; Krzysztof Gofryk, Idaho National Laboratory; Aleksandr Chernatynskiy, Missouri Science and Technology University
Tuesday 2:00 PM
February 25, 2020
Room: 18
Location: San Diego Convention Ctr
Session Chair: Cody Dennett, Idaho National Laboratory
2:00 PM Invited
Thermal Transport in Nanostructured Crystalline and Disordered Materials: Renkun Chen1; 1University of California, San Diego
Thermal transport plays an important role in a number of technologies, such as thermoelectrics, solar-thermal energy utilization, thermal barrier coatings, and so on. In the past few years, our work has focused on nanostructured materials of both the crystalline and disordered forms. In this talk, I will present our work on this front. First, we have been working on the continuous development of the instrumentation platform that enables us to precisely measure thermal conductivity and other related thermophysical properties of nanostructures, in particular in the form of nanowires and thin films. We then studied a number of nanostructures, including crystalline and amorphous Si nanowires, nanotubes, and thin films. We also studied thermal transport mediated by surface phonon polariton in amorphous SiO2, which is a polar dielectric material that supports SPhP. Finally, I will present our recent work on thermal transport behaviors in materials pertaining to solar-thermal applications.
2:30 PM
Physics-guided Machine-Learning Design of Aperiodic Superlattices with Maximum Localization of Coherent Phonons: Pranay Chakraborty1; Tengfei Ma1; Yan Wang1; Lei Cao1; 1University of Nevada, Reno
Aperiodic superlattices exhibit much lower lattice thermal conductivity than their periodic counterparts due to the localization of coherent phonons. However, finding the optimal configuration, i.e., layer thickness distribution and order of the thicknesses, to achieve the lowest possible thermal conductivity has been a daunting task. This primarily arises from a lack of knowledge of how superlattice configuration affects the behavior of coherent phonon transport and localization. In this work, we have identified several structural parameters that are strongly correlated with the lattice thermal conductivity of the aperiodic superlattice using classical molecular dynamics simulations and atomistic Green’s function simulations. We have revealed that they affect the coherent phonon band structure and thus transmission significantly. Moreover, we have found that using physics-guided machine learning, which considers both configuration and the structural parameters identified through this work altogether, can predict the thermal conductivity of aperiodic superlattice more accurately and efficiently.
2:50 PM Cancelled
Effects of Correlated Disorder on Phonon Transport across Random Interfaces: Taishan Zhu1; Giuseppe Romano1; Jeffrey Grossman1; 1Massachusetts Institute of Technology
Interfaces provide an effective opportunity to enable novel functionalities and avenues where intriguing physics occurs. In this work, we investigate the effects of correlated interfacial disorder on vibrational energy transport. More than Poisson-type randomness, we studied different types of correlated disorder with varying correlation functionals. When disorder is present, in contrast to the conventional scattering theory, our non-equilibrium Green’s function results show surprising enhancement of energy transmission for a wide spectrum of vibrational modes. To underpin the transport physics, we send probing wavepackets across the interfaces with modal resolution. These wavepacket simulations demonstrate identical frequency windows of transmission enhancement predicted by NEGF, and reveal the effects of mode conversion absent for pristine interfaces due to structural disorder. Beyond the above single-particle picture, we calculate modal correlation matrix based on Green-Kubo modal analysis. This work could help understand phonon transport across random interfaces and would be interesting to practical interface designs.
3:10 PM
Nano- and Micro-scale Thermal Transport in Swift heavy Ion Irradiated Oxides: Azat Abdullaev1; Vinay Chauhan2; Jacques O'Connel3; Vladimir Skuratov4; Arno van Vuuren3; Marat Khafizov2; Zhandos Utegulov1; 1Nazarbayev University; 2The Ohio State University; 3Nelson Mandela University; 4National Research Nuclear University
We investigated thermal transport in swift heavy ion irradiated oxide materials: Al2O3, MgO and Y3Al5O12 (YAG), irradiated by 167 MeV Xe ions at 1012 – 1014 ions/cm2 fluences. We observed ion tracks in sapphire and YAG at low dose. In Al2O3, the tracks overlap at high fluences resulting in sub-surface amorphization. Thermal transport assessment was conducted by time-domain thermoreflectance (TDTR) and spatial domain thermoreflectance (SDTR) methods. Combination of them allowed us to isolate conductivities of different damage regions characterized by distinct microstructure evolution regimes. Nanoscale thermal conductivity of thin amorphous and cross-plane conductivity in ion track regions was measured using TDTR. In-plane and cross plane thermal conductivities within ion track region was simultaneously measured using SDTR. These measurements reveal anisotropic thermal conductivity within Al2O3 ion track region. Simultaneous measurement of thermal transport parallel and normal to ion tracks presents a unique configuration to study nanoscale thermal transport in insulating materials.